Incandescent lamp cinematographic apparatus



Feb. 9, 1937. KQ RQSENBERG 2,069,851

INCANDESCENT LAMP GINEMATOGRAPHIC APPARATUS Filed oct.- 9, 1933 2sheets-sheet 1 mcANuEscb-Nf 5 /L-AMP;

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Feb. 9, 1937.

K. ROSENBERG INCANDESCENT LAMP CINEMATOGRAPHIC APPAATUS 2 Sheets-Sheet 2Filed Oct. 9, 1933 Fig. 5.

'Patented Feb. 9, 1937 UNITED STATES;

aotassl PATENT oFFicE INCANDESCENT LAMP v(D'I'NI'IMA'I)GRAPHIC APPARATUSKurt- Rosenberg, Berlin, Germany, assignor, by

mesne assignments, to American Epok Inc., New York, N. YY., acorporation of NewYork Application October ,9, 1933, Serial No. 692,884In Germany October 18, 1932 claim. (C1. 177-346) This invention relatesto'van apparatus for displaying pictures and communications by` means Itis an object'of this invention to increase the efli'ciency of such anapparatus and of the A controlling means.

Itis another object of the invention to secure correct timing betweenthe illumination controlling means andthe particular means chosen by theinvention for vswitching in an out the lamps' of the banks fed by anintermittent or alter2 nating electric current.`

v This and other objects Vand advantages of the l invention will becomemore fully apparent from the following description with reference to thedrawings. Y AIn the drawings Figs. 1 and 1c lshow a particular'switchngelement with its electrical ciruilt arrangement controlling the lamp ofthe lamp e d. Y Y

Figs. 2, 3, 4 are diagrams showing the operation of the invention. Fig.5 is a diagrammatical illustration of the apparatus, and Fig.4 6 is across section through a preferred synchronizing device used by thisinvention.

Heretofore in apparatuses of this type electromagnetic relays havebeenused arranged in series with each ofthe lamps to be controlled, and asuitable source of current. 'I'he electro-magnets of these relays werecontrolled by light responsive devices. Such relays worked comparativelyslow and were subject to arcing. They required com- 40 paratively largecontrolling currents. Y

According to this invention, discharge vessels are used instead of suchelectro-magnetic relays. Suitable discharge vessels became recentlyknown for example under the name of thym-tron.

These vessels comprise at least an anode and aI cathode, andcontrolling'means for the discharge. If between an anode and a cathodeof such vessel a voltage of predetermined magnitude is applied, adischarge 'startsl between these elec- 50 trodes and continues until theVoltage between the electrodes either ceases or drops below apredetermined value. The start of this discharge may be preventedhowever by applying a predetermined voltage, or electricalcharge, upon ameans adapted to influence the discharge between the v an extremely highresistance to the ow of curconveniences sake, the half cycle which isperanode and the cathode. These means may forma grid arranged betweenthe anode and cathode. In particular, if a gas discharge vessel of the'fthyratrontype is used, with a grid arranged between a cathode and ananode, an opposing 5.

voltage of a few Avolts applied to the grid suiiices':

to prevent the stat'of a dischargev between the "electrodes. If suchvopposing voltage is applied to the grid however after the discharge hasstarted.

then such voltage cannot interfere anymore with lo y the discharge andparticularly alter or interrupt it; The discharge only ceases if thevoltage applied between anode and cathode ceases or falls below apredetermined value. 'v i If direct current is used for feeding theanode- 16 cathode circuit' of such a switching vessel, it is necessaryto interrupt the current in order to stop the discharge. Therefore,direct current will bev used for the purpose of the invention in generalin the form of an intermittent current resulting 2U the electric currentto pass only in one direction Y' .t

from the anode to the cathode whereaslthey offer 30 rent in the oppositedirection. Therefore, only one half cycle of an alternating current willbe' permitted to pass through such a discharge vessel,

whereas the other half cycle is suppressed. For

mitted to pass'such a discharge vessel from its p anode to its cathode,may be called in this specification and the appended claims, a positivehalfwave, whereas'another half cycle of opposite di 0 rection which isYpractically suppressed by the electrifying action of the dischargeVessel may `arranged between said electrodes. 50

Referring to Fig. 1, there is shown a circuit arrangement comprising asource of current,l adischarge vessel, a lamp belonging to a lamp screenfor displaying any intended picture orl y other communication, and alight-responsive cle'- 55 anode.

vice arranged in another screen, or ileld, containing the dischargevessel.

It is to be understood that the lamp shown in this ligure represents alamp group which may consist of at least a single lamp, and that aplurality of such lamp groups are to be arranged in a screen, or field.In the same way, a plurality I of co-ordinated discharge vessels andcontrolling light-sensitive devices are to be'arranged in other fields,as will be shown more in' detail when the specification proceeds.

In Fig. 1, I is a'photo-tubel which is connected with the source'ofvoltage 2 and the grid 3 of the gas discharge vessel. The other pole ofthe source of voltage is connected to the cathode 4 which is indirectlyheated by the heating wire 6 by means of the heating battery 1. 5 is'theIn the anode circuit, in addition to the current source 8, there is thelamp 9. Iii is an adjustable resistance for the cell.

If thecell I is'not illuminated, there will be 'no voltage applied tothe'grid or onlyA a small voltage which is not suilicient to act as ablocking voltage., as the main drop of voltage of the battery 2 in thegrid circuit occursl at the large dark resistance of the cell I.

- the cell I on account of its illumination is now small, and thus' a.vlarger -voltage is applied to 'the"grid. This is now suillcient to actas .a block-l ing voltage and/the recommencement of the glow dischargeat the next positive half waveis thereby prevented. The lamp e 9 isextinguished.

This switching arrangement operates `so to speak negatively, since theillumination ofthel cell causes the lamp to be extinguished. A lm to bereproduced on a lamp iield must therefore be a negative of the pictureto be produced in lamp outlines. e

.This negative switchingv can be converted by simply exchanging the cellI and resistor il) into a. positive switching, that is, when thev cell II is illuminated the lamp 9 lights up, as shown in Fl8.'1a. The voltagedrop which now loccurs in the cell is in this arrangement equal to thevoltage which is applied to the grid 3. The positive switching" mayreadily be explained as follows:

If the cell I is notilluminated, on account oi?v itshiglrdarlrresistance there is a large voltage drop in it and thereforeat the grid -3.` v'Ihe gas discharge vessel can therefore `not passcurrent and the lampes is not lit up when the cell I is not iiiuminatedil whenl the een is illuminated its inner resistance is considerablyreduced and so small that there is only a small `drop of voltage acrossit, 'as

the main drop of voltage occurs in the high resistance I0:vv Thereforethe voltage previously applied to the 'grid I which was sufllcient toprevent any flow of current between the anode andthe cathy "ti there'isa potential lamp 9 therefore lights up when the cell is illuminated(positive)i. l

Fig. 2 shows the time curve of an alternating current. If such a voltageis applied t0 the anode of a grid-controlled gas discharge vessel("thyratron). the positive half waves ab, cd, ef and so forth will flowthrough the gas .discharge vessel and the lamp connected in series andthereby co-ordlnated with it, while the negative half wave bc. de. faand so forth. which are -shown in broken lines,- are suppressed by therectifying action of the gas discharge, vessel. Y

I f,` for example, atthe noment ti. ablocking i potential is applied tothe giid of the gas discharge vessel, so that the gas f discharge vesselcannot be ignited at the next positive vhalf wave cd, the lamp will thusno longer-light up.

If the blocking voltage is applied-for example at the moment ti,v thepassage of current through 'the gas discharge vessel and consequentlythrough the lamp will continue carried by the discharge.

which commenced at e, until the moment f when the lamp will beextinguished.

'I'he sequence of events at theremoval o f theblocking voltage issimilar. If'this is removed at the moment t1 the discharge will commenceat c and the lamp will then light up. 1li' the blocking f voltage isremoved at the moment t: the glow discharge will `commence immediatelyat this time and the lamp will immediately 1181112 up. since` at t thismoment t: in contradistinction to the moment difference between thecathodeand anode. A

- The application or removal of the blocking voltage occurs as explainedabove,v as a result of the 4illumination or other activation ofthephoto-cells co-ordinated with the individualgas discharge vessels. Theillumination-or other activation is effected by the projection of theseparate film pictures, that is, in a frequencycorresponding to thespeed of the film. A*

This iilm picture frequency is as.a rule different from the frequencyofthe alternating. cur- .rent flowing in the anode circuit of the gasdischarge vessel.A Therefore the instants t (Fig. 2) which correspond tothe application or removal of the blocking voltage, will have acontinually varying displacement in time with respect to the positivehalfwaves ab, cd and so forth of the alternating current;

From this resultLfor the picture to be transmitted upon'the lamp field,irregularitiesin time with respectto the time during which 4each D1?-ture frame appears, which as above described are due to the inaccuraciesin blocking 'or ignition rItiiis undesirable eifect which occurs when`the projector transports the nlm to be projected from one picture frameto the'other maybe explained by the action of the rotating shutter. Thisshuts of! the ray of iight from the pxpjecwr during the Amovement'of thenlm,so'that all the cells are in the dark for. a' short time. Accordingto the temporal position of this absence of illumination with respect tothe alternating current frequency irregularitieswill arise. If thenegative switching method is employed (lamps dark while cells vTheseadvantages'are yavoided if according vto illumination falls within a litaooaecr port time, l. e. also dark interval caused by the shutter. endsat B, that is the next picture frame begins, the shutter allows the beamof light to pass and the cells are illuminated or other activationcorresponding to the picture frame and the blockages and ignitionsproduced thereby commence at the instants c or e. In .this manner acompletely uniform and steady picture will appear on the lamp eld. x

According to the speed of the film the lm transport (dark interval) willoccur for example within each successive negative half wave or in thesecond or third negative half wave; itis only necessary that the pictureframe frequency and the alternating current frequency should have anintegral relation one with the other.

If the picture frequency is diminished the dark interval will beincreased, if the projector gearing is left unaltered. If the darkinterval becomes .longer than a single half wave (Fig. 4) it will be ofadvantage to havethe beginning of the dark interval AB, for examplewithin the first half l Vessel.

of the positive half -wave ab, which precedes the negative half Wave,which in this instance is assumed to produce the switching effect,

By the vremoval of illumination at A the state of the gas dischargevessel during the time ab is not changed, because at the instant A thegas discharge vessel, in the case in which the co. ordinated lamp inthe-picture is to be lit up, has

already lit up and the removal of illumination,

which with positive switching corresponds to the application of ablocking voltage, cannot interrupt the discharge through the gasdischarge vessel, as above described.

In addition the instant B may be displaced without detrimental effect toc,.as during the inlerval bc no current can pass the gas discharge waveis'available for switching.

If a still smaller `picture frequency is employed,

so that the lm transport time produced by the lowing positive half wave.In this way a com-.

pletelyr steady picture is obtained when using alternating current.

In order to obtain these advantages it is necessary that there shouldbesynchronism between the lm picture frequency and the alternating currentfrequency, and a definite phase relation between the two frequencies.The synchronism is obtained in a simple manner, for example by drivingthe film projector with a synchronous motor which' is fed by the samealternating current as the lamps and gas discharge vessels.

, Fig. 5 shows as an example a diagram of the varrangement of the wholeoi the incandescent lamp cinematograph. II is the nlm projector,V

discharge vessels.

feeding the cell grid circuit of the gasdischarge I8 is the drivingmotor `of the projector vkeyed thereto.

Thus practically the time of a complete which projects the film pictureon to a panel I2 which carries on the front side the cells I3, while onthe rear side thereof the gas discharge vessels I4 co-ordinated with thecells are'arranged. I5 is the lamp field, the lamps of which are4connected through the cable I6 withlthe appropriate gas The battery IIserves' for vessels. which is constructed as a synchronous motor and isfed from the same alternating I9 as the lamp field I5. Y

In order that the phases of the alternating current frequency and the lmpicturefreqency can be relatively varied for regulating the lm transporttime in the projection during the period of a negative half wave,the-synchronous motor and the projector are for example coupled througha rotatable coupling, as indicated at 20 in Fig. 5. In Fig. 6 a planetwheel gear (differential gear) is'illustrated diagrammatically as anexample of aV rotatable coupling. The synchronous motory I8 (Fig. 5) isfor example coupled to the shaft 2|, while the projector I'I (Fig. 5) isconnected with the shaft 22 (Fig. .6). The two shafts 2| and v22 havebevel wheels 23 and 24 The bridge shaft 25r has the two bevel wheels 26and 21 mounted loosely thereon. The shaft 25 is held in the frame 28which at 29 and 38 is formed as a bearing for the shafts 2| and 22. Theshaft 25 is secured by means of the Worm 32 and the worm-wheel 3|-screwed on to the frame 28. By turning the worm I2 the shaft 25- can beturned. If the shaft 25 is stationary, the two shafts 2| and 22 arepositively coupled together. By turning the shaft 25, however, arelative rotation of the shafts 2| and 22 bythe known differentialaction is obtained.

By regulation (rotation of the shaft 25 from the outside by means of theWorm gearing 32 'and 3|) by means of such a coupling, it is easy Alsothe control of the gas discharge vessels offers advantages as regardsthe selection of the cells which are necessary for the operation. Whilefor the operating-relays cells are necessary whichwhenilluminated giveabout 5 m. a., for

the grid control voltages of a few volts only are required and theamount of current does not come into question. Consequently alkali cellscan be used for operating the incandescent lamp cine-A matograph, whichare not suitable for use with mechanical relays as they only give acurrent of a few microamperes.

Further in order to obtain a change in voltage at the grid by means ofthe cells, only a small intensity of illumination is necessary,V so thatin this Way advantages in the operation of the film projector areobtained.

What I claim is:

1. A system for displaying pictures and communications by means of alamp screen comprising lamp groups, each group consisting of at leastone lamp; a source'of alternating current; discharge vessels comprisingat least one anode and a cathode forming a discharge gap, and acontrolling electrode, said electrode blocking the start of now ofcurrent through said gap Vat a current supply certain voltage, each ofsaid electrodes, a lamp group and said source of alternating currentconnected in series; light responsive devices disposed vin Aa screenadapted to be illuminated; a source yof blocking voltage, each of saiddevices interconnected between an electrode each and said source ofblocking voltage; means having several conditions of operation forcontrolling the illumination of said devices; and means for shifting thelast mentioned means from one condition to another one only after thestart of a positive half wave and prior to the termination of asuccessive negative hal! wave of said source of alternating current.

2. A system for displaying pictures and communications by means of alamp screen comprising lamp groups, each group consisting of at leastone lamp; a source of alternating current; discharge vessels comprisingat least one anode and a cathode forming a discharge gap, and acontrolling electrode, said electrode blocking the start of a dischargethrough said gap'at a certain voltage, each of said electrodes.- a lampgroup and said source of alternating current connected in series; lightresponsive devices disposed in a screen adapted to be illuminated; asource prising lamp-groups, each consisting of at least one lamp; asource of alternating current; discharge. vessels comprising at leastone anode, a cathode and a controlling electrode, said electrodeblocking the start of a discharge at a Acertain voltage, each of saidvessels and lamp groupsandsaid source of alternating'currentconnectedinseries; light responsive devices disposed in a screen adapted to beilluminated; a source of blocking voltage, each of said devicesconnected in'series with an electrode each and said source of blockingvoltage; means having diierent conditions of operation for controllingVthe illumination of said devices; means for vshifting 'said controllingmeans from one condition to another one, comprising a synchronous motorto vbe 4fed by said source of alternating cun'ent and an .adjustablephase changing device, said latter device capable of changing the phaseposition of said controlling means relative to said motor with respectto said alternating current,

whereby start and termination of operation of I said shifting meansvwith respect to said alternating vcurrent is controlled sothatsald'termination occurs during the negative half-waves oi! saidalternating current source.

4. An apparatus for displaying pictures and communications bymeans of alamp screen comprising lamp groups, each group consisting oi' at leastone lamp, said apparatus .to be operatedby a succession of electricalcurrent impulses separated by an interval; discharge vessels comprisingat least one anode, a cathode and an auxiliary electrode, said electrodecontrolling the start v of the discharge by the voltage to be appliedthereto, each of said vessels and lamp groups connected in serieswithrespect to the said current impulses; light responsive devicesdisposed in a screen adapted to be illuminated, each of said devicesconnected in series with an electrode each l and means for connectingsaid device with a source of controlling voltage; means having differentconditions of operation for controllingthe illumination of said devices;means for changing one of said conditions into another one, comprising asynchronous `motor to be fed by said current impulses and 'an adjustablephase changing device, said latter device lcapable oi changing the phaseposition with respect to said current impulses, whereby start andtermination of operation of said changing means with respect to saidcurrent impulses are controlled so that said termination occurs betweensaid impulses.

5. An apparatus for displaying Pictures and communications by means of alamp field to be operated by a succession of electrical intermittentcurrent impulses, comprising lamp groups i arranged in a iield, eachgroup consisting of at least one lamp; discharge vessels comprising atleastA one anode and a cathode electrode andv means controlling thedischarge betweensaid electrodes, each of said vesselsand a lamp groupeach connected in series with respect to said current impulses; lightresponsive devices disposed in a ileld adapted to be illuminated, eachof said devices interconnected with one of said controlling means eachand means for connecting said devices with a source of controllingvoltage;

means' having different conditions of operation 'I for controlling theillumination oi.' said devices;

means for changing one oi' said conditions into another one, comprisinga synchronous motor to be v fed by said current impulsesand anadjustable phase changing device, said latter device capable of changingthe phase position with respect to said current impulses, whereby startand termination of operation of said changing means with respect to saidcurrent impulses are controlled so that said termination occurs betweensaid impulses.

KURT RO.

